(a) Field of the Invention
The invention pertains to the field of reinforcing constructions for the panels of folding cartons to enable the cartons to withstand internal loading tending to burst the carton and stack loading tending to crush or collapse the carton.
(B) Description of the Prior Art
In U.S. Pat. No. 987,206 which issued on Mar. 21, 1911 to J. H. Wilson, there is disclosed a box which can be erected from separate sidewall panels of sheet metal and having a frame construction of wood or similar materials. Being of sheet metal and wood construction, the box is not a folding carton. The sheet metal sidewall panels each contain a V-shaped rib which extends vertically in the erected carton with the apex of the V-shaped rib disposed outwardly beyond the outer surface of the panel. The construction by which the reinforcing rib extends outwardly of the sidewall panel increases the envelope of the erected box for a given cubic interior volume thereof. Furthermore, the sheet metal construction of the U.S. Pat. No. 987,206 patent requires that the box have a wood frame to which the sheet metal sidewall panels are attached.
U.S. Pat. No. 3,097,781 which issued on July 16, 1963 to J. J. Masi shows a carton containing vertically extending reinforcing elements having a V-shape. The reinforcing elements can extend from an end portion of a sidewall panel and can be secured by staples or glue to hold the reinforcing element secure with respect to the interior surface of the sidewall panel. This construction requires that there be a separate panel whenever the panel is to have reinforced elements extending from the vertical edge portions of the panel. Furthermore, this construction results in the reinforcing elements being disposed within the corner portions of the carton.
A number of U.S. patents show inserts such as inserts or sleeves which are adapted to be disposed within the interior of cartons. The sleeves contain V-shaped vertically extending reinforcing elements. These patents include U.S. Pat. No. 2,618,937 which issued on Nov. 25, 1952 to E. J. Francis; U.S. Pat. No. 2,934,251 which issued on Apr. 26, 1960 to T. F. Kramer; U.S. Pat. No. 3,397,831 which issued on Aug. 20, 1968 to M. F. Adams, and U.S. Pat. No. 3,782,619 which issued on Jan. 1, 1974 to C. A. Dittbenner. The use of an insert having V-shaped ribs and being disposed within a separate carton increases the amount of carton material which must be provided and can increase the weight of the final carton for a given degree of strength. Furthermore, with the exception of the reinforcing members of the U.S. Pat. No. 3,097,781, the inserts are separate from the adjacent walls of the carton and accordingly require that loading be transmitted through the carton to the reinforcing member.